Witter, Robert C. (ORCID: 0000-0002-1721-254X) Singleton, Drake M. (ORCID: 0000-0001-5346-0623) 20251217 tabular digital data Anchorage, Alaska U.S. Geological Survey, Alaska Science Center Suggested Citation: Witter, R.C., Singleton, D.M., 2025, Radiocarbon data from Karluk Lake on Kodiak Island, Alaska: U.S. Geological Survey data release, https://doi.org/10.5066/P17SFAW6 https://doi.org/10.5066/P17SFAW6 This dataset consists of sample descriptions and radiocarbon age data from Karluk Lake on Kodiak Island, Alaska; samples were analyzed at Northern Arizona University, Arizona Climate and Ecosystems Isotope Laboratory https://in.nau.edu/aceisotopelab/. These data were collected to interpret the chronology of sediment deposited in Karluk Lake, including disturbances to the sedimentary environment that occur during flooding and earthquake shaking. 20220609 20231002 observed Complete None planned -154.12 -153.97 57.44 57.28 USGS Metadata Identifier USGS:6942112ad4be02297efc1f74 ISO 19115 Topic Category Biota GeoscientificInformation NASA GCMD Earth Science Keyword Thesaurus Earth science Land surface Tectonic uplift Glaciation USGS Thesaurus Geology Hazards Earthquakes Paleoseismology Carbon-14 analysis USGS Geographic Names Information System (GNIS) Alaska Kodiak Island Karluk Lake No access constraints. No use constraints. These data are marked with a Creative Commons Zero v1.0 (CC0-1.0) Universal public domain dedication. It is requested that this USGS data release be cited for any subsequent publications that reference or utilize these data. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. U.S. Geological Survey, Alaska Science Center Mailing and Physical

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Anchorage Alaska 99508 USA 907-786-7000 gs-ak_asc_datamanagers@usgs.gov Analyses conducted by Northern Arizona University, Arizona Climate and Ecosystems Isotope Laboratory https://in.nau.edu/aceisotopelab/. Data presented in the radiocarbon table were visually checked for inaccuracies by the lab analysts and the authors. Analyses include formal tests, including the running of standards and blanks, to assess measurement errors (see Process Step 2). Attribute values fall within expected ranges. This dataset is complete; no data were omitted. This dataset is as presented by the laboratory and augmented by the authors. Positions determined by hand-held GPS; accuracy estimated to be within 10 meters. Radiocarbon analyses were conducted at Northern Arizona University (NAU), Arizona Climate and Ecosystems (ACE) Isotope Laboratory https://in.nau.edu/aceisotopelab/. Samples submitted for analysis included detrital macrofossils in lake sediment like fragments of deciduous leaves, twigs and seeds. The C-14 dataset reports one-sigma, analytic ages in radiocarbon years before 1950 (C-14 yr BP). Unknown Sample results are reported as Fraction Modern: a measurement of the deviation of the C-14/C-12 ratio of a sample from 'Modern'. Modern is defined as 95% of the radiocarbon concentration (in AD 1950) of NBS Oxalic Acid I (SRM 4990B, OX-I) normalized to delta C-13VPDB = -19 per mil (Olsson, 1970). Errors are reported as Fraction Modern error, an external error calculated from the reproducibility of multiple exposures for a given target. The C-14/C-12 of a sample is measured 15 separate times over the course of a run. FM_err is calculated by propagation of error equations, including 1) the replication error of the standards, 2) the variation on the blanks, 3) the replication error of the sample measurement itself, and 4) the counting error of the sample. Data analysis uses BATS software (Wacker et al., 2010). Unknown Radiocarbon age (annual resolution) was calculated as follows: Age = -8033 x ln(Fm). Age is reported in radiocarbon years before 1950 (C-14 yr BP) unless Fraction Modern is >1 (i.e., later than 1950). The dataset reports analytic ages in radiocarbon years before 1950 (C-14 yr BP) and one-sigma errors. Unknown LITERATURE CITED: Olsson, I.U., 1970. The use of Oxalic acid as a Standard. in Olsson, I.U. (ed.), Radiocarbon Variations and Absolute Chronology, Nobel Symposium, 12th Proc., John Wiley and Sons, New York, p. 17. Wacker, L.,Christl, M., Synal, H.-A., 2010, BATS: a new tool for AMS data reduction. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 268(7–8):976-979. https://doi.org/10.1016/j.nimb.2009.10.078 Unknown Point 0.0001 0.0001 Decimal degrees World Geodetic System of 1984 (WGS84) World Geodetic System of 1984 (WGS84) 6378137 298.257223563 paleoseismology_C14data_KarlukLk_witter.csv Table with sample details and C-14 age analysis results. Presented in a Comma Separated Value (CSV) formatted table. Author defined File_no File number issued by Northern Arizona University (NAU), Arizona Climate and Ecosystems (ACE) Isotope Laboratory https://in.nau.edu/aceisotopelab/. Laboratory defined Unique identifier, the sample receipt number assigned by NAU ACE. Date_reported Date when ACE Isotope Lab reported the results (mm/dd/yyyy). Laboratory defined 10/2/2023 10/2/2023 Date (mm/dd/yyyy) Sample_id Sample identification provided by USGS. Author defined Field code that identifies sample including depth in sediment core. Sample_depth Sample depth in centimeters, measured in sediment core tube. Author defined 29 117.5 centimeters Source NAU ACE Lab source analyzed: EA-GIS, elemental analyzer-gas ion source; or graphite, sample converted to graphite source. Laboratory defined Entry represents the source analyzed. NAU_ACE_no A unique number that is an internal lab identifier. 'NAU' identifies the Northern Arizona University, ACE Isotope Lab, the facility that analyzed the samples. Laboratory defined Internal lab identifier F_modern Fraction Modern is a measurement of the deviation of the C-14/C-12 ratio of a sample from 'Modern'. Modern is defined as 95% of the radiocarbon concentration (in AD 1950) of NBS Oxalic Acid I (SRM 4990B, OX-I) normalized to delta C-13VPDB = -19 per mil (Olsson, 1970). Laboratory defined 0.7759 0.9667 unitless FM_err Fraction Modern error is an external error calculated from the reproducibility of multiple exposures for a given target. The C-14/C-12 of a sample is measured 15 separate times over the course of a run. FM_err is calculated by propagation of error equations, including 1) the replication error of the standards, 2) the variation on the blanks, 3) the replication error of the sample measurement itself, and 4) the counting error of the sample. Data analysis uses BATS software (Wacker et al., 2010). Laboratory defined 0.002 0.0076 unitless D_C14 D C-14 is calculated directly from fraction modern: D C-14 = (Fm - 1)*1000. Laboratory defined -224.1 -33.3 unitless D_C14_err D C-14 error is the FM error times 1000. Laboratory defined 2.0 7.6 unitless C14_Age Radiocarbon age calculated from the delta C-13-corrected Fraction Modern according to the formula: Age = -8033 x ln(Fm). Reported in radiocarbon years before 1950 (C-14 yr BP) except when Fraction Modern is >1 (>Modern). Laboratory defined 272 2038 Radiocarbon years (rounded) before 1950 CE C14_Age_err Radiocarbon age error, 1 sigma, is calculated directly from the error of fraction modern, described in the definition of C14_Age. Laboratory defined 20 71 Radiocarbon years (rounded) before 1950 CE Latitude Latitude, given in decimal degrees, datum WGS84. Measured with a recreational GPS receiver with an estimated accuracy of +/-10 m. Author defined 57.29067 57.35829 Decimal degrees (WGS84) Longitude Longitude, given in decimal degrees, datum WGS84. Measured with a recreational GPS receiver with an estimated accuracy of +/-10 m. Author defined -154.0374 -154.0076 Decimal degrees (WGS84) Material_dated Description of sample material submitted for radiocarbon dating and geologic context. Author defined Description of sample material submitted for radiocarbon dating and geologic context. U.S. Geological Survey USGS ScienceBase Team Mailing and Physical

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Denver Colorado 80225 USA 1-888-275-8747 sciencebase@usgs.gov The U.S. Geological Survey, Alaska Science Center is the authoritative source of these data, distributed by ScienceBase (a USGS Trusted Digital Repository). Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data for other purposes or on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. CSV Tabular data in CSV format; FGDC metadata in XML and HTML formats. https://doi.org/10.5066/P17SFAW6 None 20251217 U.S. Geological Survey, Alaska Science Center Mailing and Physical

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Anchorage Alaska 99508 USA 907-786-7000 gs-ak_asc_datamanagers@usgs.gov FGDC Content Standard for Digital Geospatial Metadata (CSDGM) FGDC-STD-001-1998